Development of new theoretical tools for navigating ab initio potential energy surfaces and applications of electronic structure methods to organometallic and inorganic chemistries

The dissertation is comprised of two parts---(1) the development of new tools for exploring potential energy surfaces and (2) the application of electronic structure methods to organometallic and inorganic chemistries. Since the potential energy surface construct represents a principle concept in the understanding of molecular properties and reactivity, new developments that expand the limits of theoretical chemistry are essential. We outline three specific contributions we have made in this area. Specifically, we discuss two new algorithms for reaction path following and two new approach for locating first-order saddle points, which correspond to transition structures. These new tools, as well as other state-of-the-art quantum chemical techniques, are employed in the second section to extend the understanding of some current questions and processes in organometallic and inorganic chemistries. In particular, we describe work designed to better understand the mechanism of nickel(0) catalyzed three 278 component coupling reactions, an investigation of structure and bonding preferences in a set of molecular magnet precursors, and a study of isomerization reactions for uranyl dihydroxide. These applications of electronic structure theory serve two general purposes. First, they provide descriptions of the chemistries studied that may well be classified as academic. In this way, they allow for a deeper understanding of very fundamental processes. Second, and perhaps more importantly, our work offers knowledge of trends and behaviors that are often difficult, or impossible, to ascertain using conventional experimental methods. As a result, our contributions open the door for faster and more specific tuning of desired properties by experimental colleagues.